classic car engine oil

The temperature conundrum

Engine oil viscosity is a measure of how runny it is, thus indicating its ability to coat and protect metal bearing surfaces from rubbing together metal-to-metal. Oil viscosity is quantified by a number, usually from 0 (very thin) to 90 (very thick). But this viscosity is inversely proportional to temperature, so hot oil is runnier and less able to protect big gaps as found in older engine designs, and cold oil is heavy and sluggish, draining some engine power and again reducing protection. So a fixed-grade oil has to be thick enough to protect the engine at maximum temperature but this means it will be very thick at cold temperatures, making the engine very hard to start. Cold climate drivers sometimes have to resort to heating the engine with a paraffin heater before they can be started!

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KWE has become the top specialist in rebuilding, upgrading and repairing Jaguar XJ-based cars including the XJS, DB7 and Series 1/2/3 XJ saloons. We also work with the Jaguar E type, Mark 2, XK8, X300, X308. We are within easy reach of London, the M3, M4 and M40 motorways. We are an engineering-based company where quality is paramount and customer support comes naturally.